Exfoliation generally follows denudation of the bone by accident, but not uniformly. When the periosteum is stripped off by violent injury, the bone in some cases does not lose its natural colour; granulations arise from the exposed part, and it again becomes covered without any part of its substance having been destroyed. Again, careful removal of the periosteal covering, as in excising a tumour or ulcer by the knife, may be followed by death of the outer table of the skull; small portions only separating in some cases, whilst in others a large part of the bone, and of considerable thickness, perishes. The cranial bones may in part become dead throughout their entire thickness, and separate, either after a severe bruise, or in consequence of inflammatory action following injury or arising from disease. The process of separation is either speedy or tedious, according to the vigour of the constitution. The deficiency is repaired, in a great measure, from the subjacent bone, when its whole thickness is not thrown off. But when the breach is complete, the surrounding parts assume the reparative action; the granulations from the dura mater and integuments coalesce, and a dense membrane fills up the space. The denuded bone should be kept covered and moist, and for this purpose lint frequently wetted with tepid water is the best dressing: spirituous or greasy applications can do no good. A free discharge for the matter should be afforded, and the wound kept clean. If the exfoliation goes on slowly, perforation in the dead bone may be made at different points down to the living parts, with the view of expediting the process. Exfoliations are sometimes retained by surrounding granulations overlapping their edges and confining them in their situation; or are fixed by atmospheric pressure, after separation has taken place from the parts underneath by the action of the absorbents, in the same way as a boy’s leathern sucker becomes firmly fastened to the stone to which it is applied. In such circumstances a small screw may be fixed into a perforation carefully made in the bone, and thus the dead part may be lifted out without pain or difficulty, when otherwise it might have lain for many weeks, keeping up the discharge. In this way the large sequestrum, represented at p. 240, was extracted from its bed. The powdered red precipitate of mercury may be occasionally sprinkled on the parts surrounding the dead portion, in order that the granulations embracing it may be destroyed, and the part more completely detached. The general health must be all along carefully attended to. Sarsaparilla with guaiac, sassafras, mezereon, &c., is often useful, more especially if pains in other parts continue to annoy the patient. Under such medicines he in general improves very rapidly in appetite, flesh, and strength.